Elda Markovic

Development of an in vitro reproductive screening assay for novel pharmaceutical compounds

An in vitro reproductive cell‐based toxicity assay was developed using MLTC‐1 (murine Leydig tumour cell line) in order to examine the reproductive toxicity of two novel nanopharmaceutical compounds, namely ethylene glycol mono allyl ether and poly(ethylene glycol) octa‐functionalized polyhedral oligomeric silsesquioxane. Three commonly used cytotoxicity assays, namely the MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H ‐tetrazolium bromide], MTS [3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H ‐tetrazolium] and Crystal Violet assays, were compared, and the MTT assay proved to be the most accurate and reproducible for the MLTC‐1 cell line. The doubling rate of the MLTC‐1 cells was 30±3.5 h and the optimal seeding density for the MTT assay was 20000 cells per well, and the optimized MTT assay utilized a 4 h cell adherence followed by incubation with 0.5 mg/ml MTT for 1 h. The intra‐ and inter‐assay CV (coefficient of variation) values were 12.3 and 11% respectively. MLTC‐1 cells only produce the reproductive hormone progesterone in response to hCG (human chorionic gonadotropin), which stimulated progesterone production dose‐dependently from 0 to 100 m.i.u. (milliinternational units)/ml (2706±1118 ng/ml). H2O2 as a negative control killed 100% of cells at 1000 μg/ml. The two nanopharmaceutical compounds were cytotoxic at concentrations ≥0.1 μg/ml, but hCG decreased cytotoxicity to ≥1000 μg/ml (P <0.001). hCG‐stimulated progesterone synthesis afforded some protection against the cytotoxic effects of the two novel nanotechnology compounds; therefore doses ≤100 μg/ml and an exposure period of 1 h would be recommended for testing in in vivo animal reproductive assays.

A versatile approach to grafting biofouling resistant coatings from polymeric membrane surfaces using an adhesive macroinitiator

Biofouling is a serious problem for any wetted structure, having a negative influence on applications as diverse as marine transport, implanted medical devices and water treatment. Here, we address this issue by creating a polydopamine-based coating on desalination reverse osmosis membranes incorporating a bromo-macroinitiator for subsequent polymerisation of sulfobetaine monomers into anti-biofouling polymer brushes. Surface characterisation using attenuated total reflectance-Fourier transform infrared spectroscopy and the water contact angle demonstrated the attachment of the polysulfobetaine brushes and that the hydrophilicity increased for the coated membranes. Using a macroinitiator formation time of ten minutes followed by polyzwitterion coating of one hour resulted in a 17% increase in water flux without significant effect on the salt rejection performance. These membranes also exhibited substantial suppression of protein and bacterial attachment of 69% and 88% respectively compared to unmodified membranes.

Synthesis of Strictly Alternating Siloxane Copolymers and Cyclics

Herein we report a “One-Pot” synthetic route for preparing 1,1,5,5-tetramethyl-3,3,7,7-tetraphenyl cyclo-tetrasiloxane and strictly alternating poly(dimethylsiloxane-alt-diphenylsiloxane) copolymers by heterofunctional poly-condenzation of diphenylsilanediol with dichlorodimethylsilane in the presence of two different amines, triethylamine and diethylamine, respectively. The products have been characterized by single-crystal X-ray diffraction, 1H, 13C and 29Si nuclear magnetic resonance spectroscopy, thermogravimetric analysis and differential scanning calorimeter.

Synthesis and Structure of 1,5-Di-(Ethylphenyl)-1,5-Dimethyl-3,3,7,7-Tetraphenylcycloterasiloxane: a Novel Cyclotetramer

Herein we report the first synthesis of 1,5- di-(ethylphenyl)-1,5-dimethyl-3,3,7,7-tetraphenylcyclotetrasiloxane using a new ‘One Pot’ procedure as recently reported for the preparation of strictly alternating 1,1,5,5-tetramethyl-3,3,7,7-tetraphenylcyclotetrasiloxane by the heterofunctional condensation of diphenylsilanediol with (phenylethyl)methyldichlorosilane in the presence of the ter tiary amine, triethylamine (Nguyen et al. Silicon 6:21–26 2014). The prepared 1,5-di-(ethylphenyl)-1,5-dimethyl-3,3,7,7-tetraphenylcyclotetrasi loxane was fully characterized by single-crystal X-ray diffraction, 1H, 13C and 29Si nuclear magnetic resonance spectroscopy, elemental analysis, mass spectroscopy, thermogravimetric analysis and differential scanning calori metric studies.